South American quake survey could help predict future big ones

April 26 (UPI) — A new survey of earthquakes in South America could help scientists predict the next big one.

An international team of Japanese and South American researchers analyzed the dynamics of dozens of earthquakes occurring along the fault lines of the Ecuador-Colombia subduction zone, including quakes that shook the west coast of South America in 1906, 1942, 1958, 1979 and 2016.

“The Ecuador-Colombia subduction zone, where the Nazca plate passes underneath the South American plate, is particularly interesting because of the frequency of large earthquakes there,” Hiroyuki Kumagai, an environmental scientist at Nagoya University, in Japan, said in a news release. “It’s also a good site to investigate whether the ruptures at plate boundaries causing huge earthquakes are linked to subsequent large earthquakes years or decades later.”

It’s said that all knowledge is local. The truism certainly applies to earthquakes. Though general rules of earthquake behavior can be used to analyze quakes all over the world, the behavior of every fault system is unique.

To predict future big quakes within the Ecuador-Colombia subduction zone, researchers must study its peculiarities. In the analysis, the researchers were able to link certain types of fault slips with certain types of earthquakes.

Scientists found the 1906 earthquake, the strongest of the bunch, was triggered by a different fault slip than other quakes. Their analysis also showed quakes in 1942 and 2016 were triggered by the local fault slip.

The researchers detailed their findings in the journal Geophysical Research Letters.

“Now that we can precisely link previous earthquakes to ruptures at specific sites along plate boundaries, we can gauge the risks associated with the build-up of pressure at these sites and the likely frequency of earthquakes there,” lead researcher Masahiro Yoshimoto said. “Our data also reveal for the first time differences in rupture mechanisms between oceanic trenches and deeper coastal regions in this subduction zone.”